Smith suffered a subluxation of his right shoulder when he threw his glove in the dugout after allowing an eighth-inning homer to the Oakland Athletics' Khris Davis on May 14. The Red Sox lost the game 6-5.
Smith was 1-1 with a 3.77 ERA in 18 games before the injury. He was acquired from Seattle before the 2016 season to be a setup man for closer Craig Kimbrel but has been limited to 29 games for the Red Sox. He had Tommy John surgery two years ago and returned to appear in eight games last September. On Tuesday, Red Sox trainer Brad Pearson told reporters that Smith also has issues with his labrum. Pearson said he believed the main cause of the injury was the throwing of the glove.
"There's firsts for everything," Pearson said. "It's not something I would've typically seen, but he threw it pretty hard, and it's possible we found out that's another way you can hurt your shoulder.
"He had done a really good job with all his rehab up to that point, including making his shoulder strong. I think it's a freak thing. It's unfortunate that it happened. Who knows where his arm was in space when he was throwing. Sometimes most of the injuries happen on the awkward plays. I would classify this as an awkward motion, and just bad luck."
The surgery will be performed in New York by Dr. David Altchek.